updated fractals and impact box membership based on companies house records

_coops/fractals.md

 title: Fractals
 name: Fractals
-members:
+members: 4
 website: https://fractals.coop/
 email: hello@fractals.coop
 twitter: 

_coops/impact-box.md

 title: Impact Box
 name: Impact Box
-members:
+members: 7
 website: https://impactbox.coop/
-email: hello@fractals.coop
+email: hello@impactbox.coop
 twitter: 
 github:
 address: Lytchett House Wareham Road, Lytchett Matravers, Poole, England, BH16 6FA